The binding of books by welding the edges of the pages of special paper is disclosed in our U.S. Pat. No. 3,560,290, issued Feb. 2, 1971. A number of different kinds of apparatus for welding the paper together are disclosed in that patent.
One of the advantages of welding is that since it is a clean process and requires no application of adhesive, no control of the quantity of adhesive applied and no protection of other parts of the pages and apparatus from accumulations of adhesive. The welding step is well suited to performance on machines that perform other operations on the book such as folding or collating. This invention includes welding apparatus embodied in a folding machine and also includes welding apparatus embodied in a gathering machine. Such machines will be referred to generically herein as "apparatus for assembling sheets" in a desired order.
The invention will be described in a folding machine between the last and next to last folding stations. Signatures on their way to the last folding station are welded along the line on which the last fold will be made so that when the sheets of the signature are folded at the last station, they are already bound together along the fold line and it is unnecessary to use adhesive or to sew or staple the sheets of the signature, or to trim off the folds so that adhesive can be applied to individual pages. The welded signature is bound together as strongly as any system and more strongly than most. The pages must be split to separate them; and this connection is made automatically and without slowing down the output of the folding machine.
The invention will also be described in a gathering machine in which individual pages or signatures are brought together in the sequence in which they are to be bound, and instead of transferring them to another machine for securing the sheets or signatures together, they are welded together at the delivery station, where successive assembled sheets or signatures are removed from the gathering machine. Again the operation can be automatic and performed on the gathering machine without decreasing the output of the machine. The start-up and clean-up labor of adhesive applicators is eliminated.
Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.